Abstract Number: PB0615
Meeting: ISTH 2020 Congress
Background: The ISTH SSC plasma standard is a secondary coagulation standard developed to aid manufacturers in the labelling of coagulation calibrators. Values are assigned for 24 haemostasis parameters through assessment against relevant WHO International Standards in multi-centre international collaborative studies. However, it is useful to compare results obtained on this plasma with a wide range of reagents and methods in routine laboratory use to confirm that commercial calibrants are accurately labelled.
Aims: UK NEQAS BC has regularly distributed the SSC plasma standard as a blinded sample for assay in proficiency testing exercises. We report here the first comparison of proficiency testing results to the assigned values for the lot #5 of the SSC plasma standard.
Methods: The plasma was sent to 870 centres, with a request to perform fibrinogen assays, and 385 centres for FVIII, FIX and VWF assays. Results along with method details for each assay were returned. Median results were determined, and compared to the SSC plasma standard assigned values.
Results: Table 1 shows the median results for all methods for fibrinogen, FVIII, FIX and VWF:Ag assays. Method specific VWF activity assay results are also shown. Reagent-related differences were noted, for example for FVIII:c assays, the median results for users of one widely used reference plasma was 81.3u/dl (n=187), compared to 91u/dl for users of another reference plasma (n= 52, p< 0.001).
Conclusions: it is useful to compare values assigned to commercial calibrants against the SSC plasma standard in an exercise with results obtained by a large variety of methods in a proficiency testing exercise. We have demonstrated good agreement with the assigned values for fibrinogen, FVIII, FIX, and VWF assays, including the method-specific target values for VWF activity, introduced for the first time with this lot of plasma. However, some method-related discrepancies require further investigation.
| Test | Assigned Value Lot #5 | no. of users, UK NEQAS BC | Median value, UK NEQAS BC |
| Clauss fibrinogen | 3.19g/L | 836 | 3.10g/L |
| FVIII:C | 82.0 IU/dL | 361 | 81.0 IU/dL |
| FIX:C | 109.0 IU/dL | 319 | 110.0 IU/dL |
| VWF:Ag | 114.0 IU/dL | 235 | 117.0 IU/dL |
| VWF activity Aggregometry (VWF:RCo) | 82.0 IU/dL | 37 | 82.0 IU/dL |
| Chemiluminescence (VWF:GPIbR) | 95.0 IU/dL | 18 | 97.3 IU/dL |
| IL VWF:RCo (VWF:GPIbR) | 95.0 IU/dL | 71 | 101.0 IU/dL |
| Siemens (VWF:GPIbM) | 80.0 IU/dL | 42 | 83.6 IU/dL |
| VWF:Collagen binding | 102.0 IU/dL | 42 | 102.6 IU/dL |
[Table 1. Median results compared to assigned values.]
To cite this abstract in AMA style:
Jennings I, Kitchen S, Kitchen D, Munroe-Peart S, Lowe A, Brown L, Walker I. ISTH SSC Plasma Standard Lot #5 – Results in a UK National External Quality Assessment Scheme for Blood Coagulation (NEQAS BC) Exercise [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/isth-ssc-plasma-standard-lot-5-results-in-a-uk-national-external-quality-assessment-scheme-for-blood-coagulation-neqas-bc-exercise/. Accessed October 1, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/isth-ssc-plasma-standard-lot-5-results-in-a-uk-national-external-quality-assessment-scheme-for-blood-coagulation-neqas-bc-exercise/